Mechanism for exchanging compliant members of vibrating screens

ABSTRACT

An apparatus for use in replacing a compliant member of a vibratory screen assembly. In supporting the vibratory screen assembly, the compliant member is compressed between a screen base and a contact plate that is mounted on a screen frame of the vibratory screen assembly and potential energy is stored by the compliant member as a result of the compression. The apparatus includes an exchanging plate and connectors that hold the exchanging plate at a selectively adjustable distance away from the contact plate. The potential energy stored by the compliant member may be decreased by increasing the distance between the exchanging plate and contact plate by adjusting the connectors. The compliant member may be safely removed and exchanged by eliminating all compression in the compliant member using the exchanging plate.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication No. 62/729,604, filed on Sep. 11, 2018 and entitledMECHANISM FOR EXCHANGING COMPLIANT MEMBERS OF VIBRATING SCREENS, whichis incorporated herein by reference in its entirety.

FIELD

The invention relates generally to vibratory screens. More particularly,the present invention relates to a mechanism for exchanging compliantmembers of vibrating screen.

BACKGROUND

With initial reference to FIGS. 1 and 2, there is provided aconventional vibratory screen assembly 100, which may be used toclassify and separate material into two or more differently-sizedproducts. A typical vibratory screen assembly 100 is comprised of one ormore screen decks 102 which attach to a screen frame 104 that includes apair of side plates 106. Each screen deck 102 includes a sizing medium108 such as wire cloth. The sizing media 108 has openings 110 thatdictate the largest sized material particle that can pass through themedia. An impulse mechanism (not shown) is provided to generatevibrational motion and to impart such motion to the screen deck(s) 102of the screen assembly 100. This vibration is design to stratify thematerial as it flows across the media 108 and to expose the materialparticles to the media openings 110.

Material to be classified by particle size flows across the length ofeach screen deck 102, and generally, at least some of it passes throughthe sizing media 108 as the impulse mechanism vibrates the screen deck102. The vibrations imparted to the screen deck 102 cause material smallenough to pass through the media 108 to pass through to a lower screendeck or transfer chute or conveyor. It also helps to convey the materialacross the screen deck 102 and prevents material build-up on the sizingmedia 108.

The screen frame 104 is supported by compressible compliant members 112,which are commonly formed from metal or elastomer springs, which isolatethe screen frame 104 from a screen base 114. A compliant member 112 ispositioned below each of one or more bracket assemblies 116 located onor near each corner of screen frame 104. Bracket assemblies 116 includea back plate 118 to which are attached a pair of spaced apart sidestiffeners 120. A stationary contact plate 122 is fixedly attached tothe back plate 118 and extends between and is connected to a bottom endof the side stiffeners 120. Bracket assemblies 116 are configured totransfer forces between the compliant members 112 and the side plates106. The compliant members 112 are configured to compress as acompression force, such as the weight of screen frame 104 or avibrational force, is applied to them and to decompress as thecompression force is removed or is eliminated. Compliant members 112 areconfigured to compress between the base surface 114 and the contactplate 122. Compliant members 112 compress to an equilibrium point, wherethe downwardly-directed force (e.g., the weight of screen frame 104) isequivalent to the combined upwardly-directed forces of all the compliantmembers. The number of compliant members 112 is dependent on the mass ofthe screen frame 104 and the stiffness of the compliant members 112.

At times, compliant members 112 may require replacement due to wear orto change the stiffness of the vibratory screen 100, or for otherreasons. Typically, when beginning the exchange process, compliantmembers 112 are under compression due to the weight of the screen frame104. The compliant members 112 store potential energy when compressedand an uncontrolled release of that energy could cause serious injury ordamage. Thus, in order to safely exchange compliant members 112, thepotential energy should be released prior to beginning the exchangeprocess.

One conventional method for releasing the potential energy stored in thecompliant members 112 is to convert the stored potential energy togravitational potential energy by raising the screen frame 104 off ofsome or all of the compliant members. Raising the screen frame 104allows the compliant members 112 to decompress, at which point thecompliant members can be safely exchanged. Frequently, the liftingdevice used in raising the screen frame 104 is a counterweighted craneor a mechanical jack. Such lifting devices may require several operatorsworking in tandem to complete the task of exchanging the compliantmembers 112. These lifting devices also may not be readily available atthe locations which the vibratory screen assemblies 100 are located.Consequently, replacing compliant members 112 in a screen frame 104according to conventional methods may require significant down time asthe proper equipment is re-located. Additionally, raising a screen frame104 with respect to screen base 114 is inherently dangerous due to thepotential of the screen frame falling.

What is needed, therefore, is a method and apparatus that enablescompliant members to be quickly and easily swapped without requiringraising the screen frame.

Notes on Construction

The use of the terms “a”, “an”, “the” and similar terms in the contextof describing embodiments of the invention are to be construed to coverboth the singular and the plural, unless otherwise indicated herein orclearly contradicted by context. The terms “comprising”, “having”,“including” and “containing” are to be construed as open-ended terms(i.e., meaning “including, but not limited to,”) unless otherwise noted.The terms “substantially”, “generally” and other words of degree arerelative modifiers intended to indicate permissible variation from thecharacteristic so modified. The use of such terms in describing aphysical or functional characteristic of the invention is not intendedto limit such characteristic to the absolute value which the termmodifies, but rather to provide an approximation of the value of suchphysical or functional characteristic.

Terms concerning attachments, coupling and the like, such as “attached”,“connected” and “interconnected”, refer to a relationship whereinstructures are secured or attached to one another either directly orindirectly through intervening structures, as well as both moveable andrigid attachments or relationships, unless otherwise specified herein orclearly indicated as having a different relationship by context. Theterm “operatively connected” is such an attachment, coupling orconnection that allows the pertinent structures to operate as intendedby virtue of that relationship.

The use of any and all examples or exemplary language (e.g., “such as”and “preferably”) herein is intended merely to better illuminate theinvention and the preferred embodiments thereof, and not to place alimitation on the scope of the invention. Nothing in the specificationshould be construed as indicating any element as essential to thepractice of the invention unless so stated with specificity.

SUMMARY

The above and other needs are met by an apparatus for use in replacing acompliant member of a vibratory screen assembly. As described above,when supporting the vibratory screen assembly, compliant members arecompressed between a base surface and a movable contact plate of thevibratory screen assembly and potential energy is stored by thecompliant members as a result of the compression. In a preferredembodiment of the present invention, the apparatus includes anexchanging plate and connectors that hold the exchanging plate at aselectively adjustable distance away from the contact plate. Thepotential energy stored by the compliant member may be decreased byincreasing the distance between the exchanging plate and contact plateby adjusting the connectors. The compliant member may be safely removedand exchanged by eliminating all compression in the compliant memberusing the exchanging plate.

Certain preferred embodiments of the present invention provide a screenassembly system. The system includes a vibratory screen assemblyconfigured to classify and separate material into two or moredifferently-sized products based on the size of the material. Bracketassemblies mounted to the vibratory screen assembly include a movablecontact plate and a compliant member. The compliant member compressesbetween a base surface and the movable contact plate when supporting thescreen assembly. The compliant member stores potential energy as aresult of that compression. The system also includes exchanging platesand connectors. The connectors connect one of the exchanging plates toone of the contact plates and hold the exchanging plate at a selectivelyadjustable distance away from the contact plate. The potential energystored by the compliant member may be increased by decreasing thedistance between the contact plate and the exchanging plate. Increasingthe potential energy stored in one of the compliant members reduces thepotential energy stored in the other compliant members. Conversely, thepotential energy stored by the compliant member may be decreased byincreasing the distance between the contact plate and the exchangingplate. Decreasing the potential energy stored in one of the compliantmembers increases the potential energy stored in the other compliantmembers. The potential energy stored in a compliant member may bereduced entirely until the compliant member is no longer compressed and,at that point, the compliant member may be safely removed. Preferably,the bracket assemblies are arranged and configured such that, after thepotential energy stored by the compliant member of at least one bracketassembly is decreased entirely, the vibratory screen assembly can beentirely supported by the remaining bracket assemblies.

A preferred embodiment of the present invention provides a method forremoving a compliant member from a vibratory screen assembly. The methodincludes the steps of providing a vibratory screen assembly having aplurality of bracket assemblies, connecting a movable contact plate toeach bracket assembly at a selected vertical position such that thecontact plate is prevented from moving vertically, and supporting thevibratory screen frame above a base surface by compressing compliantmembers between the base surface and each of the contact plates.Potential energy stored by the compressed compliant members isequivalent to the weight of the frame such that the frame is located ata first equilibrium vertical position. The method further includes thesteps of removably connecting an exchange plate to a selected onemovable contact plate at a selectively adjustable distance via one ormore connectors and disconnecting the selected one movable contact platefrom the bracket assembly such that the contact plate can movevertically within the bracket assembly. The method further includes thesteps of increasing the distance between the exchange plate and theselected one movable contact plate until the compliant member isdecompressed, removing the decompressed compliant member from betweenthe base surface and the selected one movable plate, and supporting thevibratory screen frame above the base surface by compressing theremaining compliant members between the base surface and the contactplates. Potential energy stored by the remaining compressed compliantmembers is equivalent to the weight of the screen frame such that thescreen frame is located at a second equilibrium vertical position thatis different from the first equilibrium vertical position.

BRIEF DESCRIPTION OF THE DRAWINGS

Further advantages of the invention are apparent by reference to thedetailed description when considered in conjunction with the figures,which are not to scale so as to more clearly show the details, whereinlike reference numerals represent like elements throughout the severalviews, and wherein:

FIG. 1 is a perspective view depicting a conventional screen assemblyincluding compliant members;

FIG. 2 is detail view of a bracket assembly and the compliant members ofFIG. 1 enclosed within a circle identified by the letter “A”;

FIG. 3 is a perspective view of removable exchanging plates according toan embodiment of the present invention;

FIG. 4 is a top plan view illustrating exchanging plates positionedaround a compliant member in a screen assembly according to anembodiment of the present invention;

FIG. 5 is a front elevation view of a compliant member supporting abracket assembly according to an embodiment of the present invention,showing the compliant member compressed to an equilibrium point;

FIG. 6 is a front elevation view of the bracket assembly of FIG. 5 withexchanging plates positioned around the compliant member;

FIG. 7 is a front elevation view depicting the bracket assembly of FIGS.5 and 6 with connectors partially removed from a contact plate and thecompliant member partially decompressed;

FIG. 8 is a front elevation view depicting the bracket assembly of FIGS.5-7 with connectors almost entirely removed from contact plate and thecompliant member fully decompressed.

FIG. 9 is a front elevation view of a bracket assembly with apermanently attached exchange plate according to an alternativeembodiment of the present invention;

FIG. 10 is a bottom perspective view of the bracket assembly of FIG. 9;

FIG. 11 is a front elevation view of a screen assembly having a heightretention device according to an embodiment of the present invention;and

FIG. 12 is detail view of a bracket assembly and the height retentiondevice of FIG. 11 enclosed within a circle identified by the letter “B”.

DETAILED DESCRIPTION

Referring now to FIGS. 3 and 4, there is provided a pair of removableexchange plates 200 and a modified bracket assembly 202 for use inexchanging compliant members 112 of a vibrating screen frame 104according to an embodiment of the present invention.

Like bracket assembly 116 (shown in FIGS. 1 and 2) bracket assembly 202includes a back plate 201 joined between a pair of side stiffeners 203.Bracket assembly 202 also includes a movable contact plate 205 that ispositioned between side stiffeners 203. However, unlike bracket assembly116, the contact plate 205 of bracket assembly 202 is not fixedlyconnected to either the back plate 201 or either of the side stiffeners203. Instead, contact plate 205 is free to move vertically within avertically-oriented slot formed by the back plate 201 and the sidestiffeners 203.

Additionally, in preferred embodiments, exchange plates 200 areremovably attached to the bracket assembly 202 using a plurality ofthreaded connectors 204. Connectors 204 are preferably inserted throughopenings 207 formed in contact plate 205 and corresponding openings 206formed in each of the exchange plates 200 and then held securely by anut (not shown). These aligned openings 207, 206 are shown best in FIG.4, where a portion of the contact plate 205 is shown positioned withinbracket assembly 202. Alternatively, one or both of openings 207, 206may be threaded such that connectors 204 may be held securely withoutthe use of a nut.

By connecting exchange plates 200 to contact plate 205 with connectors204, the compression in compliant member 112 mounted to a vibratingscreen frame 104 may be relieved in a controlled, gradual fashion andwithout requiring the vibrating screen assembly to be lifted. Relievingthis compression without lifting the vibrating screen frame 104 enablesthe compliant member 112 to be exchanged more easily and in a much saferand faster manner than was previously possible.

When in use, exchanging plates 200 are preferably placed on opposingsides of the compliant member 112 (e.g., front and back) and are sizedand configured to substantially surround the compliant member.Preferably, the plates 200 are sized to fit between the compliant member112 and the side plate 106 of the screen frame 104. While a singleexchange plate 200 could be used, the installation process is simplifiedusing a pair of separate plates, as shown. Each plate 200 preferably hasa curved inner face 208 (FIG. 3) that generally follows the curvature ofthe compliant member 112. In this case, compliant member 112 is ahelical spring having a diameter (when viewed from one end) and thecurved inner face 208 has a diameter equal to or greater than thediameter of the compliant member. The plates 200 are preferablyinitially spaced slightly vertically below the bottom end of the bracketassembly 202. Connectors 204 are passed through contact plate 205 andeach exchanging plate 200 and are then secured with nuts. To decreasethe distance between the contact plate 205 and exchanging plate 200, thenut is tightened. Conversely, to increase the distance between thecontact plate 205 and exchanging plate 200, the nut is loosened.

With reference now to FIG. 5, contact plate 205 is preferably removablyattached to and between the side stiffeners 203 with fasteners 210.Fasteners 210 may be passed through first openings 212 in sidestiffeners 203 and then through corresponding second openings 214 inupwardly-curved and vertically disposed left and rights ends 216 ofcontact plate 205 (or vice versa). The threaded ends of the fasteners210 are retained within the bracket assembly 202 by a nut 218. Inalternative embodiments, at least one of opening 212 or opening 214 isthreaded and threaded ends of the fasteners 210 may be threaded into theopening to connect the side stiffeners 203 with the contact plate 205.

The bracket assembly 202 of FIG. 5 is shown in its normal operatingconfiguration. In this configuration, the compliant member 112 iscompressed by the weight of the screen frame 104 and, due to thatcompressive force, if fasteners 210 were removed from openings 212, 214,the compliant member 112 would decompress quickly and the contact plate205 could be carried suddenly upwards by the top of the compliant memberwith respect to the back plate 201 and side stiffeners 203. Putdifferently, if fasteners 210 were removed from openings 212, 214, thescreen frame 104 could fall suddenly with respect to the screen base114. For that reason, attempting to remove the compliant member 112 orthe fasteners 210 from openings 212, 214 in this configuration would bequite dangerous. Thus, as mentioned above, in order to safely exchangecompliant members 112, the potential energy must be released to avoid anuncontrolled release of the built up potential energy.

Referring to FIG. 6, exchanging plates 200 are placed on opposing sidesof the compliant member 112 (e.g., front and back). The plates 200 maybe initially spaced slightly vertically below the bottom end of thebracket assembly 202. Connectors 204 removably connect contact plate 205to exchanging plates 200. The connectors 204 may be fixed by a nut (orother suitable fixing mechanism) or may be threaded into either thecontact plate 205 or the exchanging plates 200. Preferably, thisconnection prevents the exchanging plates 200 from moving towards orfurther away from the contact plate 205 when such movement is notdesired. The distance between the exchanging plate 200 and the contactplate 205 is limited to the length of the portion of the connectors 204that connect them together. As such, the distance between the exchangingplate 200 and the contact plate 205 is fixed and preferably is preventedfrom increasing or decreasing by connectors 204. As the nut is threadedfurther onto the connectors 204 (or connector is threaded further intothe exchanging plate 200 or contact plate 205), the exchanging plate isdrawn towards the contact plate and into contact with the bottom ofbracket assembly 202. In this particular embodiment, the exchangingplates 200 contact the bottom end of side stiffeners 203 and back plate201. This contact prevents the exchanging plate 200 from moving furtherupwards. On the other hand, as the nut is threaded off of the connectors204 (or connector is threaded out of the exchanging plate 200 or contactplate 205), the exchanging plate is separated from the contact plate.

Once the exchanging plate 200 has been brought into contact with thebracket assembly 202, the fasteners 210 can be removed from both theside stiffeners 203 and the contact plate 205 by the operator. Removingthe fasteners 210 disconnects the contact plate 205 from the bracketassembly 202, which allows the contact plate to move vertically withrespect to the bracket assembly. More particularly, the contact plate205 can move vertically within the vertical slot defined by the backplate 201 and the side stiffeners 203. This vertical movement is guidedby the slot and the positioning of the contact plate 205 with respect tothe bracket assembly 202 is determined by the connectors 204.

The force of the weight of the screen frame 104 is transmitted throughthe bracket assembly 202 downwards onto the exchanging plates 200. Thatforce is then carried through connectors 204 up to contact plate 205.Finally, the force is then transmitted down to compliant member 112 viacontact plate 205. Thus, the weight of the screen frame 104 is stillborne (i.e., indirectly) by the compliant members 112, even though thebracket assembly 202 is not rigidly connected to the contact plate 205.Importantly, since the screen frame 104 is at the equilibrium point(i.e., the point where the entire weight of screen frame 104 is borne bythe compliant members 112), the compliant members do not compressfurther when fasteners 210 are removed; rather, the compliant members112 are already fully compressed under the weight of the screen frame104.

Since the contact plate 205 is no longer mounted to the bracket assembly202, the contact plate can be moved upwards between side stiffeners 203if the compliant member 112 decompresses. Similarly, the contact plate205 can be moved downwards between side stiffeners 203 if the compliantmember 112 compresses (i.e., if connectors 204 were tightened further).However, when the fasteners 210 are first removed, the contact plate 205remains stationary. The contact plate 205 does not move because thelength of the compliant member 112 remains fixed by the connectors 204connecting the contact plate to the exchanging plate 200 and by contactbetween the exchanging plates 200 and bracket assembly 202. As such, thecompliant member 112 does not compress or decompress and the position ofthe contact plate 205 within the bracket assembly 202 remains fixed.

Referring to FIG. 7, the operator may then gradually unthread theconnectors 204 evenly from the exchanging plate 200 to increase thelength of the portions of the connectors that separate the exchangingplate and the contact plate 205. As that length increases, the compliantmember 112 slowly expands and decompresses, which raises the contactplate 205 between the side stiffeners 203, as evidenced by themis-alignment of opening 212 with opening 214. Unthreading theconnectors 204 from the exchanging plate 200 transfers the potentialenergy in the compliant member 112 being exchanged to the remainingcompliant members 112 that support the screen frame 104. In other words,the weight of the screen frame 104 bearing on the compliant member 112that is being removed is transferred to the other compliant members.

As the weight of the screen frame 104 is transferred, the remainingcompliant members 112 temporarily experience a greater compressive forceand the equilibrium point of the screen assembly is lowered slightly asthe compliant members compress further under the added weight. Once thecompliant member 112 is fully decompressed, as shown in FIG. 8, theconnectors 204 are loosened further. As the connectors 204 unthread fromthe exchanging plate 200, the exchanging plates 200 are brought out ofcontact with the bottom of the bracket assembly 202. It is not necessaryto fully decompress the compliant member 112 or to loosen connector 204until exchanging plate 200 separates from bracket assembly 202. Thecompliant member 112 could be removed from the bracket assembly 202 evenwhile it is under compression. However, the separation of the exchangingplate 200 from the bracket assembly 202 is a safety assurance feature ofthe invention. Once this separation occurs, the operator can be assuredthat compliant member 112 has been fully decompressed and can be safelyremoved.

In order for the new compliant member 112 to be installed, theabove-described process is reversed. Once the new compliant member 112has been correctly positioned below the contact plate 205, a portion ofthe potential energy stored in each of the remaining compliant memberscan be transferred to the replacement compliant member. The connectors204 associated with the replacement compliant member 112 are graduallytightened until holes 212, 214 are aligned. This tightening processtransfers potential energy from the other compliant members 112 to thenew, replacement compliant member. At that point, fasteners 210 arere-inserted through openings 212, 214 and tightened in order tore-connect the contact plate 205 with the bracket assemblies 202.Connector 204 may then be loosened entirely and removed from contactplate 205 and bracket assemblies 202. Lastly, exchanging plates 200 maybe removed, which returns compliant member 112 and screen frame 104 toregular operation.

With reference now to FIGS. 9 and 10, there is provided bracketassemblies 300 that include integrated exchanging plates 302 accordingto an alternative embodiment of the present invention. Bracket assembly300 includes back plate 304 and a pair of side stiffeners 306 that areattached to the back plate, and contact plate 308 that is removablyattached to and between the side stiffeners 306 by fasteners 310. Inthis particular embodiment, integrated exchanging plates 302 are mountedto and extend inwards (i.e., towards each other) from a bottom end ofthe bracket assembly 300. When replacing compliant member 112,connectors 312 are inserted through openings 314 in exchanging plates302 and corresponding openings 316 in contact plate 308 in order to fixthe distance between the contact plate and the exchanging plate. Whenthe distance between contact plate 302 and exchanging plate 302 isfixed, the fasteners 210 can be safely removed from side stiffeners 306in a similar manner as discussed above.

An alternative embodiment is illustrated in FIGS. 11 and 12. Thisembodiment employs height retention device 400 in conjunction withbracket assembly 202 (or 300) and to permit the exchange of compliantmembers without transferring potential energy to other compliant members112. The height retention device 400 is positioned below the screenframe 104 and maintains the equilibrium height of the screen frame 104while the compliant member 112 is exchanged utilizing the same processas described previously. The height retention device 400 may take theform of a hydraulic jack or block which is used to maintain theequilibrium height of the screen frame 104, but not to raise the screenassembly.

Although this description contains many specifics, these should not beconstrued as limiting the scope of the invention but as merely providingillustrations of some of the presently preferred embodiments thereof, aswell as the best mode contemplated by the inventor of carrying out theinvention. The invention, as described herein, is susceptible to variousmodifications and adaptations as would be appreciated by those havingordinary skill in the art to which the invention relates.

What is claimed is:
 1. An apparatus for use in replacing a compliantmember of a vibratory screen assembly, wherein the compliant member iscompressed between a screen base and a movable contact plate that ismounted on a screen frame of the vibratory screen assembly and potentialenergy is stored by the compliant member as a result of the compression,the apparatus comprising: an exchanging plate; and one or moreconnectors configured to connect the exchanging plate to the contactplate and to hold the exchanging plate at a selectively adjustabledistance away from the contact plate, wherein the potential energystored by the compliant member may be increased by decreasing saiddistance and the potential energy stored by the compliant member may bedecreased by increasing said distance.
 2. The apparatus of claim 1further comprising a height retention device positioned under the screenframe configured to maintain the vertical position of the screen framewith respect to the screen base as said distance between the contactplate and the exchanging plate is increased.
 3. The apparatus of claim 1wherein each of the one or more connectors comprises a bolt having athreaded end and a corresponding nut configured to thread onto thethreaded end, the bolt sized to pass through corresponding alignedopenings formed in the contact plate and the exchanging plate.
 4. Theapparatus of claim 1 further comprising: a bracket assembly having: aback plate configured to mount to said screen frame; a pair of sidestiffeners mounted to and extending outwards from the back plate; avertical slot defined by the back plate and the side stiffeners; saidmovable contact plate, which is configured to slide vertically upwardsand downwards within the vertical slot and to be fixedly mounted betweenthe side stiffeners at a selected vertical position in the verticalslot; a pair of exchanging plates positioned between the contact plateand the screen base, each of which exchanging plates has an inner face;and an open area formed between the inner faces of the exchanging platesthat is sized to allow the compliant member to extend from the screenbase, through the open area, and to contact the contact plate.
 5. Theapparatus of claim 4 wherein the exchanging plates are fixedly mountedto the side stiffeners and extend inwards towards the compliant member.6. The apparatus of claim 4 wherein the exchanging plates are movablevertically upwards and downwards with respect to the bracket assemblyand are guided vertically by the one or more connectors and eachexchanging plate is configured to removably engage at least one sidestiffener and, through that engagement, to be prevented from movingfurther vertically upwards.
 7. The apparatus of claim 6 wherein eachexchanging plate is configured to engage both side stiffeners.
 8. Theapparatus of claim 4 further comprising fasteners configured to engageboth the side stiffeners and the contact plate in order to fix thecontact plate at said selected vertical position.
 9. The apparatus ofclaim 8 further comprising vertically disposed left and right endsformed on the contact plate that are each disposed adjacent an innersurface of one of the side stiffeners and are each engaged by at leastone of said fasteners for fixing the contact plate at the selectedvertical position.
 10. A screen assembly system comprising: a vibratoryscreen assembly configured to classify and separate material into two ormore differently-sized products based on the size of the material, saidvibratory screen assembly comprising a screen frame and a screen base; aplurality of bracket assemblies mounted to the screen frame of thevibratory screen assembly, each bracket assembly including: a movablecontact plate; and a compliant member configured to compress between thescreen base upon which the screen frame is supported and the movablecontact plate when supporting the screen frame and to store potentialenergy as a result of that compression; one or more exchanging plates;and connectors configured to connect the one or more exchanging platesto a contact plate of a selected one of the plurality of bracketassemblies and to hold the one or more exchanging plate at a selectivelyadjustable distance away from the contact plate, wherein the potentialenergy stored by the compliant member may be increased by decreasingsaid distance, which reduces the potential energy stored in the othercompliant members, and the potential energy stored by the compliantmember may be decreased by increasing said distance, which increases thepotential energy stored in the other compliant members, wherein thebracket assemblies are arranged and configured such that, after thepotential energy stored in the compliant member of the selected bracketassembly is decreased entirely, the vibratory screen assembly can betemporarily entirely supported by one less than the plurality of bracketassemblies, so that the compliant member can be removed and replaced.11. The system of claim 10, the screen assembly comprising: one or morescreen decks, each screen deck having a sizing medium; and the screenframe, including a pair of side plates, each of which has anoutwardly-facing surface and an inwardly-facing surface and wherein eachof the bracket assemblies is mounted to the outwardly-facing surface ofone of the side plates and the one or more screen decks are disposedadjacent the inwardly-facing surface of the side plates.
 12. The systemof claim 11 wherein the one or more exchanging plates are sized to fitbetween the compliant members of the plurality of bracket assemblies andthe outwardly-facing surface of the side plates.
 13. The system of claim10 wherein each bracket assembly further comprises: a back plateconfigured to mount to said screen frame; a pair of side stiffenersmounted to and extending outwards from the back plate; a vertical slotdefined by the back plate and the side stiffeners, wherein said movablecontact plate is configured to slide vertically upwards and downwardswithin the vertical slot and to be fixedly mounted between the sidestiffeners at a selected vertical position in the vertical slot; and apair of exchanging plates each having an inner face, wherein eachexchanging plate is positioned between the contact plate and the screenbase; an open area formed between the inner faces of the exchangingplates that is sized to allow the compliant member to extend from thebase surface, through the open area, and to contact the contact plate.14. The system of claim 13 wherein the compliant member has asubstantially circular cross-section having a radius.
 15. The system ofclaim 14 wherein the compliant member is a helical spring.
 16. Thesystem of claim 14 wherein the exchanging plates extend inwards towardsa vertical center of the back plate and terminate at an inner facehaving a radius.
 17. The system of claim 16 wherein the radius of theinner face is greater than the radius of the compliant member.
 18. Amethod for removing a compliant member from a vibratory screen assemblycomprising a screen frame that is vibrationally isolated from a screenbase by a plurality of compliant members, the method comprising thesteps of: A. providing the vibratory screen assembly with a plurality ofbracket assemblies, one for each compliant member; B. connecting amovable contact plate to each bracket assembly at a selected verticalposition such that the contact plate is prevented from movingvertically; C. supporting the vibratory screen frame above the basescreen by compressing the plurality of compliant members between thescreen base and each of the contact plates, wherein potential energystored by the compressed compliant members is equivalent to the weightof the screen frame such that the screen frame is located at a firstequilibrium vertical position with respect to the screen base; D.removably connecting an exchange plate to a selected one of the contactplates at a selectively adjustable distance via one or more connectors;E. disconnecting the selected one of the contact plates from the bracketassembly such that the contact plate can move vertically; F increasingthe distance between the exchange plate and the selected one of theplates until the compliant member is decompressed; G. removing thedecompressed compliant member from between the screen base and theselected one of the contact plates; and H. supporting the vibratoryscreen assembly above the screen base by compressing the remainingcompliant members between the screen base and the contact plates whichare contacted by the remaining compliant members, wherein potentialenergy stored by the remaining compressed compliant members isequivalent to the weight of the screen frame such that the screen frameis located at a second equilibrium vertical position with respect to thescreen frame that is different from the first equilibrium verticalposition.
 19. The method of claim 18 further comprising the steps of: I.placing an uncompressed compliant member between the screen base and aselected one of the contact plates; and J. reducing the distance betweenthe exchange plate and the selected one of the contact plates tocompress the uncompressed compliant member.
 20. The method of claim 19wherein the distance between the exchange plate and the selected one ofthe contact plates is reduced until the screen assembly is located atthe first equilibrium vertical position.